Case Studies

EMERGENCY CONTROL SYSTEM REPLACEMENT

Executive Summary:

A fire destroyed the entire control system for the melting and holding furnaces at the cast house plant of an aluminum extruder. Panels, controllers, terminations, operator interfaces…everything destroyed. Production halted. The plant needed a new control system ASAP. Kredit Automation and Controls was asked to help make it happen. The relationship goes back more than twenty years and Kredit Automation is a crucial, strategic vendor for this plant. Kredit redeployed resources and immediately started designing a panel, developing a control system and leading the customer and the other contractors on wiring, instrumentation and installation. In less than a month, with the guidance and consultation of combustion experts from CEC Combustion Safety, the plant was melting and casting again. This required a level of responsiveness, flexibility and versatility that no vendor can match.

Project Details:

On an otherwise normal production morning a gas leak caused a fire that destroyed the control room of the melting and holding furnaces. Fortunately no one was in the room and no one in the area got hurt. But the control panels and operator stations were obliterated and the cast house production ceased. The daily revenue losses were huge. This was as bad as a situation could be short of serious injury or death. Fortunately, the two furnaces themselves were not severely damaged and could be run after some repairs to valves and other instruments—but only after a complete new control system was created and a large amount of rewiring was done. The entire gas train on the melter had to be replaced and the holding furnace had to be completely rewired.

Kredit Automation was called immediately and asked to help. There was no time for bids or engineering studies…this system had to be put back into operation as soon as possible. Normal engineering lead times would be far too long and had to be avoided.

Significant challenges loomed:

• Old, incomplete prints that weren’t correct and had mixed up line sheets and drawings from prior revisions and other models produced by the OEM. Some were just lost.

• Damaged field devices and instruments such as the gas and air valves and transmitters that had to be replaced fast. The entire gas train on the melting furnace had to be replaced. Other instruments needed upgrades for compatibility.

• Damaged and aging wire throughout the system. Damaged raceways and conduits that had to be replaced. A major rewire job was required. In the case of the holding furnace it was a complete rewire job.

• No PLC program for one unit and a very arcane and uncommented program for the other. The program was deemed unusable…too risky to waste time trying to glean information from it in the compressed time frame. New programs had to be written. But first the correct combustion control strategy had to be designed.

Kredit began immediately with all available resources and some resources that were diverted for this emergency. With focused effort and careful study on site, the challenges from missing and incorrect drawings and documentation were overcome. We started creating drawings within days. A new panel was produced that included a ControlLogix L17S safety controller. Research on combustion control strategies was successfully done to obtain a cascade PID loop control strategy that could be adapted to this system. These control strategies were adopted and applied to the development of the new combustion control system programs within days. New operator interfaces with graphic screens were created in a Rockwell PanelView Plus operator station.

As one might expect, many issues arose around wiring, reconstruction, and instrumentation. Initially other contractors were responsible for these tasks. It became apparent that some leadership and help were needed in various areas and Kredit Automation soon took a lead role in supervising and helping with a lot of the work needed to get things done. This was not initially forecast but became a necessity and was well received by the customer.

In summary, a working pair of melting and holding furnaces were rewired, re-instrumented and reprogrammed, and restarted in just a few weeks to get a grateful customer back in production. This is the caliber of automation professionals that will be working on your projects and the kind of dedication you can expect from Kredit Automation and Controls.

Case Studies

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